基于损伤的黏聚力弱化-摩擦角强化模型对大型地下洞室群围岩稳定性的影响

岩体的峰后强度对大型地下洞室群围岩开挖变形稳定具有较大影响.针对此问题,采用基于损伤的黏聚力弱化-摩擦角强化(cohesion weakening and friction strengthening,CWFS)模型并以动态链接库(dynamic link library,DLL)的形式植入FLAC3D程序中,针对依托...

Effects of a Damage-based CWFS Model on the Stability of Rock Masses in Large Underground Caverns

The post-peak strengths of rock masses have a great influence on the stabilities and deformations of large underground caverns. To analyze the stability of the large underground caverns of a power station, a damage-based model, CWFS (cohesion weakening and friction strengthening) model which was implanted into the FLAC3D program in the form of DLL (dynamic link library), was used to simulate the excavation process of the underground caverns, considering and ignoring the excavation damages of the rock masses, respectively. By analyzing the characteristics of the deformation, stress, plastic zones and damage zones of the surrounding rock masses and comparing them with the on-site monitoring results, the effects of the excavation damages on the stability were studied. The results show that: compared with those calculated by ignoring the excavation damage, (a) the stresses calculated by considering the damage were released with higher degrees, which is not conducive to the stability; (b) the plastic zones and deformations in the crown and high walls of the powerhouse cavern are increased to 1.5 to 2.0 times. (c) The CWFS model can effectively reveal the inducements of the plastic zones, i.e. those with damage factors ranging from 0.5 to 1.0 are caused by the excavation unloading while those ranging from 0 to 0.5 are caused by the excavation disturbance. (d) The deformation magnitudes and trends calculated by the model are similar to the on-situ data monitored by multi-point displacement meters, while those calculated by ignoring the damage are underestimated and dangerous.